Container for storing a liquid at a low temperature

ABSTRACT

951,923. Laminates. CONCH INTERNATIONAL METHANE Ltd. Jan. 28, 1963 [March 12, 1962], No. 3468/63. Heading B5N. [Also in Divisions B7 and F4] A container for liquefied gas comprises a rigid shell 13 lined with heat insulating panels 3, 4, the edges of adjacent panels being shaped so that there is a gap between adjacent panels widening in the direction of the inner surface of the panels, the gap being filled with a sealing material 28, e.g. polyvinyl chloride foam compressed to at least 90% of its free volume, and being closed by a thin scab 16, e.g. of plywood or maple glued in position. The panels 4 are formed of a honeycomb core 20 filled with foamed-in-place polyurethane and faced with plywood 21 and 22 which is bonded to the core 20, and the panels 3 are formed of a balsa wood core 23 faced with plywood 24 and 25 bonded to the core 23.

D. K. TUCKER Nov. 26, 1963 CONTAINER FQR STORING A LIQUID AT A LOW TEMPERATURE Filed March 12, 1962 2 Sheets-Sheet l O R M M W m D. K. TUCKER Nov. 26, 1963 2 Sheets$heet 2 Filed March 12, 1962 1' I e TUIBJI /v o w 0a m w x w /v 8 A/uv 2 0 W I m /2 I a D I INVENTOR. OElMAR K TUCKER United States Patent 3,112,843 CONTABNER FGR STQRENG A LTQUID AT A LBW TEMPERATURE Delmar K. Tucker, Louisville, Ky, assiguor to Conch International Methane Limited, Nassau, Bahamas, a

corporation of the Bahamas Filed Mar. 12, E62, Ser. No. 178,824 13 Claims. (Cl. 228-) The invention relates to a container for storing a liquid at a low temperature, in particular for storing liquefied methane at about atmospheric pressure, comprising a rigid shell internally lined with heat-insulating panels and an inner tank located within the space enclosed by the heatinsulated shell.

"The temperature of the liquid stored in the inner tank is low. In the case of liquefied methane stored at about atmospheric pressure, the temperature is, for example, as low as 16l C. The inner tank is made of a material which does not lose its strength and ductility at the low temperature of the cargo. Suitable materials for the inner tank are, for example, aluminum or stainless steel. In the case Where the inner tank fails, cold liquid will flow out of it. This cold liquid should never reach the rigid shell, since the shell is normally made of a material which will lose its strength and ductility when cooled down to the very low temperature of the liquid cargo. Therefore, the heat-insulating panels must be mounted on the inner surface of the rigid shell in such a way that, in the caes of failure of the inner tank, the cold liquid cannot pass through the panels or through the joints of adjacent panels. In view of the large temperature variations which occur in the container, large expansions and contractions of the heat-insulating panels can be expected. This means that the sealing between adjacent panels must be constructed in a special way so that, notwithstanding the large expansions and contractions, the liquid-tightness is maintained under all conditions.

Containers of the above type are known. The known cotnainers are often complicated and not always fully reliable. Another :disadvatnage or the known containers is that the installation of the panels is diiiicu-lt, timeconsuming and expensive.

it is an object of the invention to provide a container of the above type which has the advantage that it is sim ple, reliable and inexpensive and which has, moreover, the advantage that the panels can be installed and the sealing between adjacent panels can be made with a minimum amount of labor.

The container according to the invention diiters from the known containers of the above kind in that it comprises heat-insulating panels spaced from the inner surface or" the rigid shell, fixing strips secured to the inner surface of the shell, the outer edge of each panel being bonded to the inner surface of a fixing strip in such a way that adjacent panels are interconnected by said fixing strip, each panel being moreover kept in place by studs secured to the inner surface of the shell and located between the fixing strips, a gap widening in the direction or" the inner surface of the panels being present between adjacent panels, said gap being filled with a sealing material and being closed by a thin scab.

Preferably the outer edge of each panel is bonded to the inner surface of the fixing strip by means of glue. A suitable material for filling the gaps between adjacent panels is foamed plastic.

The invention will now be further explained with reference to the drawings, in which- FIG. 1 shows schematically a vertical cross-section of a ship which is provided with the container according to the invention;

FIG. 2 shows a detailed view on an enlarged scale of 3,1 l2,643- Patented Nov. 26, 1963 a horizontal cross-section of a corner part of the container according to the invention;

FIG. 3 shows two adjacent heat-insulating panels in cross-section fixed to the rigid shell; and

FIG. 4 relates to the pattern according to which the panels and fixing strips are distributed over the rigid she-ll.

In FIG. 1, a vertical cross-section of a ship for transporting liquefied gases at about atmospheric pressure and having a hull i4 is shown. Ships of this type are preferably provided with an inner hull 13, which serves as the rigid shell of the container. Therefore, in the following, the inner hull 13 will be called the rigid shell 13. The rigid shell 13 is internally lined with heat-insulating material =11, 12, 15. In the space enclosed by the heatinsulated rigid shell 13, inner tanks 19 preferably made of aluminum or stainless steel, are present.

The rigid shell 13 is internally provided with timber fixing strips 1. These strips 1 must be installed in such a way that the inner surfaces of the strips 3. of each wall will lie in a flat plane, The strips 1 must be firmly attached to the inner surface of the shell 1 3 and should be supported by means of a leveling cement or mastic 17. The fixing strips It are spaced at regular intervals along the shell 13.

The heat-insulating panels used along the bottom wall and in the horizontal and vertical corner parts of the container are preferably of the type having a balsa wood core. The remaining heat-insulating panels are preferably of the type having a honeycomb core. The lastmentioned panels are indicated in the drawings by the numeral 4.. The panels 4 comprise a honeycomb core 2i and faces 2d and 22, the h-oneyoombs of the core 2% being filled with foamed-in-place polyurethane or a similar suitable plastic. By filling the honeycombs of the core 2%) in the above way, resistance to the migration of gas is improved and furthermore better heat insulation is obtained. The faces 21 and 22 are made of suitable plywood and they are bonded to the core by a suitable adhes1ve.

The panels having a balsa wood core are indicated in the drawings by the numeral 3. The panels 3 comprise a balsa wood core 23 and plywood faces 24 and 25, bonded to the core by a suitable adhesive.

The panel edges are beveled to form a cavity between adjacent panels when the panels are installed.

The heat-insulating panels are supported by the fixing strips 1 which are attached to the rigid shell 13. The outer edge of each panel contacts the inner surface of a fixing strip 1. Said outer edge and said fixing strip 1 are bonded by means of a suitable adhesive or glue. In this way, adjacent panels are interconnected in such a. way that a fluid-tight joint is formed. The panels are held in place by means of threaded studs 2 welded in place against the shell 13 by means of automatic stud welding equipment. The out-er faces 21 and 24 of the panels 4 and 3 are provided with relatively small holes 5. Larger holes 6 in alignment with each hole 5 are also present in the panels. The stud 2 extends through the hole 5 and into the larger hole 6. The threaded end of the stud 2 is provided with a washer 7 and a nut 8. By tightening the nuts 8, the panels are firmly secured in place and pressed against the fixing strips 1. The holes 6 are preferably filled with a suitable foamed plastic, for example with polyvinyl chloride foam. This filling material is indicated by the number 18. Preferably, a wooden plug 19 is driven into the studhole 6 until it is flush with the plywood face of the panel. Three-ply glass fiber cloth patches 2% are laminated over the studhole 6 with cold setting resin to seal the hole 6.

The studs 2 and the fixing strips 1 are distributed in the panel area in the way shown in FIG. 4. In order to aiiaoaa give the panels an extra su ort intermediate fixin strins n D L 2.7 can be used.

As mentioned above, the edges of the panels are beveled as shown in FIGS. 2 and 3. The cavity thus formed between adjacent panels is filled with polyvinyl chloride foam 28 or a similar suitable material, compressed to at least 90% of its free volume. The gaps between adjacent panels are closed by a scab 16 of plywood. The scab 16 must overlap the panels on each side of the joint. The scab 16 is bonded to the panel faces by using a suitable adhesive or glue.

As already mentioned, the heat-insulating panels on the floor and in the corner parts of the container are preferably of the kind having a balsa wood core. FIG. 2 shows a typical section through a vertica. corner part of the container. The balsa wood cored panels 3 are additionally supported by fixing strips 29. The gap between these corner panels 3 is filled with foamed plastic material 30 which is of the same type as the material in the gap between the other adjacent panels. A corner scab 3d closes the gap betwen the adjacent corner panels 3 and the space between the scab 31 and the gap fille with the foamed plastic 3% is in turn filled with a fillet 33. The scab 31 is preferably made of strong plywood and the fillet 33 is preferably formed of balsa wood. The opposite side of the gap can also be closed by a scab 32, if desired. The scab 32 can be formed of plywood but it is preferable to form the scab of a glass fiber fabric impregnated with a polyester resin.

The fixing strips 1 supporting the corner panels 3, are preferably further provided with metal angles 3d alongside the lateral edges away from the corners which provide additional anchorage for the corner panels 3 against movement due to contractive forces of adjacent panels.

In the container according to the invention normally use is made of heat-insulating panels having a balsa wood core and of panels having a honeycomb core. In that case, the floor and also the corner parts of the container are provided with panels having a balsa wood core, the remaining panels being of the type having a honeycomb core. This is the most economical construction. It is, however, also possible, of course, to use only panels of the type having a balsa wood core. The latter construction is also technically sound; a disadvantage is, however, that large quantities of the rather expansive balsa wood are necessary. Tnereforc, the first-mentioned construcion is usually preferred.

The top layer of insulating material 15 is preferably glass wool or a similar material. This material is rather elastic and it leaves the tank 16 free to expand and contract vertically.

The balsa wood-cored heat-insulating panels used for covering the floor of the container provide a strong support for the inner tank 16.

The container according to the invention is in particular destined for storin or transporting liquefied gases at about atmospheric pressure, such as liquefied nitrogen, liquefied air, liquefied oxygen, liquefied natural gm, liquefied methane, liquefied ethane, liquefied propane, liquefied butane, etc.

The spaces between the rigid shell .13 and the heat insulating panels cm be filled with a heat-insulating material. Preferably, bloclcs of polyurethane foam, properly compounded, are used for this purpose. Because of their structure and resistance to moisture, the blocks will hold their shape and place.

1 claim:

1. A container for storing a liquid at a low temperature, in particular for storing liquefied methane at about atmospheric pressure, comprising a rigid shell internally lined with heat-insulating panels spaced from the inner surface of the rigid shell, a tank located within the heatinsulated rigid shell, fixing strips secured to the inner surface of the shell, the outer edge of each panel being bonded to the inner surface of a fixing strip in such a way that adjacent panels are interconnected by said fixing strip, each panel being moreover kept in place by studs secured to the inner surface of the shell and located between the fixing strips, :1 gap widening in the direction of the inner surface of the panels being present between adjacent panels, said gap being filled with a sealing material and being closed by a thin scab.

2. The container as claimed in claim 1 in which the outer edge of each panel is bonded to the inner surface of the fixing strip by means of glue.

3. The container as claimed in claim 1 in which the gap between adjacent panels is filled with foamed plastic.

4. The container as claimed in claim 1 in which the gap between adjacent panels is filled with polyvinyl chloride foam.

5. The container as claimed in claim 1 in which the scab closing the gap between adjacent panels is a plywood strip.

6. The container as claimed in claim 1 in which the scab closing the gap between adjacent panels is a maple batten.

7. The container as claimed in claim 1 in which the gap is V-shaped.

8. The container as claimed in claim 1 in which each panel is provided with a thin strong outer face, said face being provided with a relatively small hole, the panel having also a larger hole in alignment with the small hole, a stud extending through the small hole, a washer and a nut being secured on the end of the stud so that the panel is pressed against the fixing strips along its outer edges, the larger hole being filled with a scaling material and being closed by a scab.

9. The container as claimed in claim 1 in which the panels have a honeycomb core, the spaces in the honeycomb material being filled with foamed plastic.

10. The container as claimed in claim 1 in which the panels have a balsa wood core.

11. The container according to claim 1 in which the adjacent panels of each pair of panels located in the corner part of the container are interconnected by an inner and an outer scab, a gap being present between the panels, said gap being filled by a sealing material.

12. The container as claimed in claim ll in which the panels located in the corner parts of the container are of the type having a balsa wood core and in which the other panels are of the type having a honeycomb core.

13. The container according to claim 1 in which the heat-insulating panels covering the floor of the container are of the type having a balsa wood core.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A CONTAINER FOR STORING A LIQUID AT A LOW TEMPERATURE, IN PARTICULAR FOR STORING LIQUEFIED METHANE AT ABOUT ATMOSPHERIC PRESSURE, COMPRISING A RIGID SHELL INTERNALLY LINED WITH HEAT-INSULATING PANELS SPACED FROM THE INNER SURFACE OF THE RIGID SHELL, A TANK LOCATED WITHIN THE HEATINSULATED RIGID SHELL, FIXING STRIPS SECURED TO THE INNER SURFACE OF THE SHELL, THE OUTER EDGE OF EACH PANEL BEING BONDED TO THE INNER SURFACE OF A FIXING STRIP IN SUCH A WAY THAT ADJACENT PANELS ARE INTERCONNECTED BY SAID FIXING STRIP, EACH PANEL BEING MOREOVER KEPT IN PLACE BY STUDS SECURED TO THE INNER SURFACE OF THE SHELL AND LOCATED BETWEEN THE FIXING STRIPS, A GAP WIDENING IN THE DIRECTION OF THE INNER SURFACE OF THE PANELS BEING PRESENT BETWEEN ADJACENT PANELS, SAID GAP BEING FILLED WITH A SEALING MATERIAL AND BEING CLOSED BY A THIN SCAB. 